@@ -1612,8 +1612,8 @@ int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low,
unsigned long ipi_bitmap_high, u32 min,
unsigned long icr, int op_64_bit);
-void kvm_define_shared_msr(unsigned index, u32 msr);
-int kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
+void kvm_define_user_return_msr(unsigned index, u32 msr);
+int kvm_set_user_return_msr(unsigned index, u64 val, u64 mask);
u64 kvm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc);
u64 kvm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc);
@@ -651,8 +651,7 @@ static int vmx_set_guest_msr(struct vcpu_vmx *vmx, struct shared_msr_entry *msr,
msr->data = data;
if (msr - vmx->guest_msrs < vmx->save_nmsrs) {
preempt_disable();
- ret = kvm_set_shared_msr(msr->index, msr->data,
- msr->mask);
+ ret = kvm_set_user_return_msr(msr->index, msr->data, msr->mask);
preempt_enable();
if (ret)
msr->data = old_msr_data;
@@ -1144,9 +1143,9 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
if (!vmx->guest_msrs_ready) {
vmx->guest_msrs_ready = true;
for (i = 0; i < vmx->save_nmsrs; ++i)
- kvm_set_shared_msr(vmx->guest_msrs[i].index,
- vmx->guest_msrs[i].data,
- vmx->guest_msrs[i].mask);
+ kvm_set_user_return_msr(vmx->guest_msrs[i].index,
+ vmx->guest_msrs[i].data,
+ vmx->guest_msrs[i].mask);
}
@@ -7922,7 +7921,7 @@ static __init int hardware_setup(void)
host_idt_base = dt.address;
for (i = 0; i < ARRAY_SIZE(vmx_msr_index); ++i)
- kvm_define_shared_msr(i, vmx_msr_index[i]);
+ kvm_define_user_return_msr(i, vmx_msr_index[i]);
if (setup_vmcs_config(&vmcs_config, &vmx_capability) < 0)
return -EIO;
@@ -162,24 +162,29 @@ module_param(force_emulation_prefix, bool, S_IRUGO);
int __read_mostly pi_inject_timer = -1;
module_param(pi_inject_timer, bint, S_IRUGO | S_IWUSR);
-#define KVM_NR_SHARED_MSRS 16
+/*
+ * Restoring the host value for MSRs that are only consumed when running in
+ * usermode, e.g. SYSCALL MSRs and TSC_AUX, can be deferred until the CPU
+ * returns to userspace, i.e. the kernel can run with the guest's value.
+ */
+#define KVM_MAX_NR_USER_RETURN_MSRS 16
-struct kvm_shared_msrs_global {
+struct kvm_user_return_msrs_global {
int nr;
- u32 msrs[KVM_NR_SHARED_MSRS];
+ u32 msrs[KVM_MAX_NR_USER_RETURN_MSRS];
};
-struct kvm_shared_msrs {
+struct kvm_user_return_msrs {
struct user_return_notifier urn;
bool registered;
- struct kvm_shared_msr_values {
+ struct kvm_user_return_msr_values {
u64 host;
u64 curr;
- } values[KVM_NR_SHARED_MSRS];
+ } values[KVM_MAX_NR_USER_RETURN_MSRS];
};
-static struct kvm_shared_msrs_global __read_mostly shared_msrs_global;
-static struct kvm_shared_msrs __percpu *shared_msrs;
+static struct kvm_user_return_msrs_global __read_mostly user_return_msrs_global;
+static struct kvm_user_return_msrs __percpu *user_return_msrs;
#define KVM_SUPPORTED_XCR0 (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \
| XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \
@@ -294,9 +299,9 @@ static inline void kvm_async_pf_hash_reset(struct kvm_vcpu *vcpu)
static void kvm_on_user_return(struct user_return_notifier *urn)
{
unsigned slot;
- struct kvm_shared_msrs *locals
- = container_of(urn, struct kvm_shared_msrs, urn);
- struct kvm_shared_msr_values *values;
+ struct kvm_user_return_msrs *msrs
+ = container_of(urn, struct kvm_user_return_msrs, urn);
+ struct kvm_user_return_msr_values *values;
unsigned long flags;
/*
@@ -304,73 +309,73 @@ static void kvm_on_user_return(struct user_return_notifier *urn)
* interrupted and executed through kvm_arch_hardware_disable()
*/
local_irq_save(flags);
- if (locals->registered) {
- locals->registered = false;
+ if (msrs->registered) {
+ msrs->registered = false;
user_return_notifier_unregister(urn);
}
local_irq_restore(flags);
- for (slot = 0; slot < shared_msrs_global.nr; ++slot) {
- values = &locals->values[slot];
+ for (slot = 0; slot < user_return_msrs_global.nr; ++slot) {
+ values = &msrs->values[slot];
if (values->host != values->curr) {
- wrmsrl(shared_msrs_global.msrs[slot], values->host);
+ wrmsrl(user_return_msrs_global.msrs[slot], values->host);
values->curr = values->host;
}
}
}
-void kvm_define_shared_msr(unsigned slot, u32 msr)
+void kvm_define_user_return_msr(unsigned slot, u32 msr)
{
- BUG_ON(slot >= KVM_NR_SHARED_MSRS);
- shared_msrs_global.msrs[slot] = msr;
- if (slot >= shared_msrs_global.nr)
- shared_msrs_global.nr = slot + 1;
+ BUG_ON(slot >= KVM_MAX_NR_USER_RETURN_MSRS);
+ user_return_msrs_global.msrs[slot] = msr;
+ if (slot >= user_return_msrs_global.nr)
+ user_return_msrs_global.nr = slot + 1;
}
-EXPORT_SYMBOL_GPL(kvm_define_shared_msr);
+EXPORT_SYMBOL_GPL(kvm_define_user_return_msr);
-static void kvm_shared_msr_cpu_online(void)
+static void kvm_user_return_msr_cpu_online(void)
{
unsigned int cpu = smp_processor_id();
- struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu);
+ struct kvm_user_return_msrs *msrs = per_cpu_ptr(user_return_msrs, cpu);
u64 value;
int i;
- for (i = 0; i < shared_msrs_global.nr; ++i) {
- rdmsrl_safe(shared_msrs_global.msrs[i], &value);
- smsr->values[i].host = value;
- smsr->values[i].curr = value;
+ for (i = 0; i < user_return_msrs_global.nr; ++i) {
+ rdmsrl_safe(user_return_msrs_global.msrs[i], &value);
+ msrs->values[i].host = value;
+ msrs->values[i].curr = value;
}
}
-int kvm_set_shared_msr(unsigned slot, u64 value, u64 mask)
+int kvm_set_user_return_msr(unsigned slot, u64 value, u64 mask)
{
unsigned int cpu = smp_processor_id();
- struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu);
+ struct kvm_user_return_msrs *msrs = per_cpu_ptr(user_return_msrs, cpu);
int err;
- value = (value & mask) | (smsr->values[slot].host & ~mask);
- if (value == smsr->values[slot].curr)
+ value = (value & mask) | (msrs->values[slot].host & ~mask);
+ if (value == msrs->values[slot].curr)
return 0;
- err = wrmsrl_safe(shared_msrs_global.msrs[slot], value);
+ err = wrmsrl_safe(user_return_msrs_global.msrs[slot], value);
if (err)
return 1;
- smsr->values[slot].curr = value;
- if (!smsr->registered) {
- smsr->urn.on_user_return = kvm_on_user_return;
- user_return_notifier_register(&smsr->urn);
- smsr->registered = true;
+ msrs->values[slot].curr = value;
+ if (!msrs->registered) {
+ msrs->urn.on_user_return = kvm_on_user_return;
+ user_return_notifier_register(&msrs->urn);
+ msrs->registered = true;
}
return 0;
}
-EXPORT_SYMBOL_GPL(kvm_set_shared_msr);
+EXPORT_SYMBOL_GPL(kvm_set_user_return_msr);
static void drop_user_return_notifiers(void)
{
unsigned int cpu = smp_processor_id();
- struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu);
+ struct kvm_user_return_msrs *msrs = per_cpu_ptr(user_return_msrs, cpu);
- if (smsr->registered)
- kvm_on_user_return(&smsr->urn);
+ if (msrs->registered)
+ kvm_on_user_return(&msrs->urn);
}
u64 kvm_get_apic_base(struct kvm_vcpu *vcpu)
@@ -7512,9 +7517,9 @@ int kvm_arch_init(void *opaque)
goto out_free_x86_fpu_cache;
}
- shared_msrs = alloc_percpu(struct kvm_shared_msrs);
- if (!shared_msrs) {
- printk(KERN_ERR "kvm: failed to allocate percpu kvm_shared_msrs\n");
+ user_return_msrs = alloc_percpu(struct kvm_user_return_msrs);
+ if (!user_return_msrs) {
+ printk(KERN_ERR "kvm: failed to allocate percpu kvm_user_return_msrs\n");
goto out_free_x86_emulator_cache;
}
@@ -7547,7 +7552,7 @@ int kvm_arch_init(void *opaque)
return 0;
out_free_percpu:
- free_percpu(shared_msrs);
+ free_percpu(user_return_msrs);
out_free_x86_emulator_cache:
kmem_cache_destroy(x86_emulator_cache);
out_free_x86_fpu_cache:
@@ -7574,7 +7579,7 @@ void kvm_arch_exit(void)
#endif
kvm_x86_ops.hardware_enable = NULL;
kvm_mmu_module_exit();
- free_percpu(shared_msrs);
+ free_percpu(user_return_msrs);
kmem_cache_destroy(x86_fpu_cache);
}
@@ -9705,7 +9710,7 @@ int kvm_arch_hardware_enable(void)
u64 max_tsc = 0;
bool stable, backwards_tsc = false;
- kvm_shared_msr_cpu_online();
+ kvm_user_return_msr_cpu_online();
ret = kvm_x86_ops.hardware_enable();
if (ret != 0)
return ret;
Rename the "shared_msrs" mechanism, which is used to defer restoring MSRs that are only consumed when running in userspace, to a more banal but less likely to be confusing "user_return_msrs". The "shared" nomenclature is confusing as it's not obvious who is sharing what, e.g. reasonable interpretations are that the guest value is shared by vCPUs in a VM, or that the MSR value is shared/common to guest and host, both of which are wrong. "shared" is also misleading as the MSR value (in hardware) is not guaranteed to be shared/reused between VMs (if that's indeed the correct interpretation of the name), as the ability to share values between VMs is simply a side effect (albiet a very nice side effect) of deferring restoration of the host value until returning from userspace. "user_return" avoids the above confusion by describing the mechanism itself instead of its effects. Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> --- arch/x86/include/asm/kvm_host.h | 4 +- arch/x86/kvm/vmx/vmx.c | 11 ++-- arch/x86/kvm/x86.c | 101 +++++++++++++++++--------------- 3 files changed, 60 insertions(+), 56 deletions(-)